Method of controlling water production through treating proppants with rpms

ABSTRACT

Water production from a subterranean formation is inhibited or controlled by pumping a fluid containing coated particles through a wellbore into the formation. The particles have been previously coated with a relative permeability modifier (RPM). Upon contact with water, the RPM coating expands or swells and inhibits and controls the production of water. The RPM may be a water hydrolyzable polymer having a weight average molecular weight greater than 100,000. The particles may be conventional proppants or gravel.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. Patent ApplicationSer. No. 12/606,464 filed Oct. 27, 2009; issued as U.S. Pat. No. ______on ______, incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to methods of inhibiting the production ofwater from subterranean formations during hydrocarbon recoveryoperations, and more particularly relates, in one non-limitingembodiment, to substances for and methods of inhibiting and controllingwater production using coated proppants.

TECHNICAL BACKGROUND

Unwanted water production is a major problem in maximizing thehydrocarbon production potential of a subterranean well. Tremendouscosts may be incurred from separating and disposing of large amounts ofproduced water, inhibiting the corrosion of tubulars contacted by thewater, replacing corroded tubular equipment downhole, and surfaceequipment maintenance. Shutting off unwanted water production is anecessary condition to maintaining a productive field.

Different methods and materials have been used to treat near-wellboresubterranean formations to selectively control unwanted water productionin the oil industry. The goal is to maximize hydrocarbon productionwhile minimizing and controlling the production of water. Pumping orsqueezing certain materials, such as relative permeability modifiers(RPMs), into subterranean formations forms a water-blocking matrixwithin the formation to control the water flow while not affecting theflow of oil and/or gas therefrom. RPMs thus reduce the permeability ofwater relative to hydrocarbons such as oil and gas.

The permeability adjustment of the formation is sometimes referred to aswater flow regulation, or more simply as water regulation. Water controland profile modification have been routinely performed using a varietyof polymers, such as polyacrylamide, cellulose and xanthan gum.

The conventional manner of RPM applications for water control involvespumping the RPM into a formation matrix that is a highly heterogeneousporous media. Unfortunately, the RPM is hard to uniformly distribute,and it is easy to inadvertently generate formation damage in theformation matrix in the process.

It would thus be desirable to discover a method which could improve thecontrol of unwanted water production from subsurface formations andimprove distribution of the water control agent, while minimizingformation damage.

SUMMARY

There is provided in one non-limiting embodiment a method of controllingwater production from a subterranean formation that concerns introducingparticles coated with a relative permeability modifier (RPM) into asubterranean formation through a wellbore. The method further involvescontacting the coated particles with water, causing swelling of the RPMthereby inhibiting water flow.

There is additionally provided in one non-restrictive version, a methodof controlling water production from a subterranean formation where themethod involves coating a particle (e.g. gravel or proppant) with arelative permeability modifier (RPM) and then mixing the coated particlewith a carrier fluid. The coated particle and carrier fluid areintroduced into a subterranean formation through a wellbore adjacent thesubterranean formation, and the coated particle or proppant is placed inthe subterranean formation. The coated particle is then contacted withwater, such as water from the formation, which causes the RPM coated onthe particle to swell thereby inhibiting water flow.

There is also provided, in another non-limiting form, treated particles(e.g. proppants or gravel) which involve a plurality of proppantparticles having a relative permeability modifier (RPM) coated thereon.

Alternatively there are provided in one non-restrictive embodimentparticles coated with a relative permeability modifier (RPM) which aremade by a process involving at least partially hydrolyzing a RPM in aliquid selected from the group consisting of water, brine, glycol,ethanol and mixtures thereof. A plurality of particles is contacted withthe liquid containing the RPM. The liquid is at least partiallyvaporized, thereby leaving a coating of the RPM on the particles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of the pressure differential of crosslinked VF-1copolymer coated on 20-60 mesh (850-250 micron) HSP® proppant at 200° F.(93° C.) with diesel and simulated formation brine (SFB); and

FIG. 2 is a graph of a comparison of a base proppant pack and a VF-1copolymer coated proppant pack at 200° F. (93° C.) with diesel andsimulated formation brine (SFB).

DETAILED DESCRIPTION

It has been discovered that unwanted subterranean formation waterproduction may be controlled or inhibited by a method involving treatingproppants with relative permeability modifiers (RPMs), and incorporatingthe coated proppants in the fluids used for hydraulic fracturing,frac-packing, and gravel-packing treatments of the formations. Theproppants or gravel may be pre-treated or coated with RPMs on thesurface before pumping them in a carrier fluid downhole.

Generally, the RPMs are relatively high molecular weight polymers thathave components or functional groups that anchor or affiliate or attachonto the surface of the proppant particle. The RPMs also are hydrophilicand/or hydrolyzable meaning they swell or expand upon contact withwater. The proppant may be sand, ceramic beads or metal beads. The sizeof the proppant may range from 10 mesh to about 200 mesh (from about2000 microns to about 75 microns). The loading of the RPMs may be onepound of RPM per 100 to 5000 pounds of proppant.

The RPM-treated proppant will form proppant fracture beds, proppantpacks or gravel packs as special porous media in downhole and nearwellbore regions to control unwanted formation water flowing into thewellbore while not adversely affecting the flow of oil and gas. Whenwater flows into the special porous media, the RPM polymers anchored onthe proppant expand to reduce the water flow channel and increase theresistance to water flow. When oil and/or gas flow through this specialporous media, the RPM polymers shrink to open the flow channel for oiland/or gas flow. The RPM pre-treated proppants are expected to formhomogeneous porous media with the RPM uniformly distributed in thedownhole and near wellbore region to increase the efficiency of the RPMcontrolling unwanted water production and to avoid formation damage.

In more detail, suitable RPMs include water hydrolyzable polymers havinga weight average molecular weight greater than 100,000. Suitable, morespecific examples of RPMs include, but are not necessarily limited to,homopolymers and copolymers of acrylamide, sulfonated or quaternizedhomopolymers and copolymers of acrylamide, polyvinylalcohols,polysiloxanes, hydrophilic natural gum polymers and chemically modifiedderivatives thereof. Crosslinked versions of these polymers may also besuitable, including but not necessarily limited to, crosslinkedhomopolymers and copolymers of acrylamide, crosslinked sulfonated orquaternized homopolymers and copolymers of acrylamide, crosslinkedpolyvinylalcohols, crosslinked polysiloxanes, crosslinked hydrophilicnatural gum polymers and chemically modified derivatives thereof.Further specific examples of suitable RPMs include, but are notnecessarily limited to, copolymers having a hydrophilic monomeric unit,where the hydrophilic monomeric unit is selected from the groupconsisting of ammonium and alkali metal salt ofacrylamidomethylpropanesulfonic acid (AMPS), a first anchoring monomericunit based on N-vinylformamide and a filler monomeric unit, where thefiller monomeric unit is selected from the group consisting ofacrylamide and methylacrylamide. Additional suitable RPMs include, butare not necessarily limited to, copolymers of vinylamide monomers andmonomers containing ammonium or quaternary ammonium moieties, copolymersof vinylamide monomers and monomers comprising vinylcarboxylic acidmonomers and/or vinylsulfonic acid monomers, and salts thereof, andthese aforementioned copolymers further comprising a crosslinkingmonomer selected from the group consisting of bis-acrylamide,diallylamine, N,N-diallylacrylamide, divinyloxyethane,divinyldimethylsilane.

More information about RPMs suitable to be of use in the method andcompositions described herein may be found in U.S. Pat. Nos. 5,735,349;6,228,812; 7,008,908; 7,207,386 and 7,398,825, all of which areincorporated by reference herein in their entirety.

With respect to the particles coated by the RPMs as described by themethods herein, otherwise conventional proppants or gravel may be used.Proppants are known in the oilfield as sized particles typically mixedwith fracturing fluids to hold open fractures after a hydraulicfracturing treatment. Proppants are sorted for size and sphericity toprovide an effective conduit for the production of oil and/or gas fromthe reservoir to the wellbore. “Gravel” has a particular meaning in theoilfield relating to particles of a specific size or specific size rangewhich are placed between a screen that is positioned in the wellbore andthe surrounding annulus. The size of the gravel is selected to preventthe passage of sand from the formation through the gravel pack. Aprimary objective of the gravel is to stabilize the formation whileminimizing inhibition of well productivity.

The particles, e.g. proppants or gravel, may suitably be a variety ofmaterials including, but not necessarily limited to, sand (the mostcommon component of which is silica, i.e. silicon dioxide, SiO₂), glassbeads, ceramic beads, metal beads, bauxite grains, walnut shellfragments, aluminum pellets, nylon pellets and combinations thereof. Theparticles may range in size from about 10 mesh to about 200 mesh (fromabout 2000 microns to about 75 microns).

The particles may be coated by a method that involves at least partiallyhydrolyzing the RPM in a liquid including, but not necessarily limitedto, water, brine, glycol, ethanol and mixtures thereof. The particlesare then intimately mixed or contacted with the liquid to contact thesurfaces of the particles with the RPM. The liquid is then at leastpartially vaporized or evaporated through vacuum, or the use of heatand/or contact with a dry gas such as air, nitrogen, oxygen or the like.The coating method may be conducted at a temperature between ambient upto about 200° F. (about 93° C.), to facilitate quick drying of thecoating. It may not be necessary in some embodiments to completely drythe coating.

The loading of the RPM on the particles may range from one pound of RPMto about 100 to about 5000 pounds of particle (1 kilogram of RPM toabout 100 to about 5000 kilograms of particle). Alternatively, the RPMloading may range from one pound of RPM independently to about 200pounds to about 1000 pounds of particle, e.g. proppant, where“independently” means any combination of the mentioned lower and upperthresholds.

The fluids into which the coated particles may be placed include, butare not necessarily limited to, water-based, oil-based, foam-based,emulsion-based, solvent-based and liquid gas-based fracturing fluids,frac-pack fluids and gravel-packing fluids. It should be understood thatpolymer hydrolyzation is a relatively slow process, and although theRPMs swell when contacted with water, the carrier fluid may bewater-based. During the pumping period, the RPM coated on the proppantsmay hydrolyze or swell slightly, but will not interfere with theproppant placement and pumping because of the relatively small amount ofRPM loading and the dried or partially dried coating. The RPM coatedparticles may be added at any suitable selected stage during a treatmentand does not have to be added throughout the typical proppant stages,e.g. only in the initial, middle or latter proppant stages. Differentsizes and/or different densities of proppants may be RPM-coated, in onenon-limiting instance, lightweight (LWPs) and ultra-lightweightproppants (ULWPs) would also be suitable for the methods andcompositions described herein. Combinations of these various materialsand procedures may be used.

The invention will now be illustrated with respect to certain exampleswhich are not intended to limit the invention in any way but simply tofurther illustrated it in certain specific embodiments.

EXAMPLES

FIG. 1 is a graph of the pressure differential of crosslinked VF-1copolymer coated on 20-60 mesh (850-250 micron) HSP® proppant at 200° F.(93° C.) with diesel and simulated formation brine (SFB). HSP proppantis available from Carbo Ceramics. VF-1 is a cross-linkedvinylamide-vinylsulfonate copolymer. The HSP proppants were coated withthe VF-1 polymer as described above. The polymer loading is 0.4% bw (byweight) of the proppant weight. FIG. 1 is a response test graph showingthat the pressure differential of the polymer-coated proppant placedinside of a 12-inch long, 1-inch ID stainless steel tube (about 30 cmlong by about 2.5 cm ID) changes when pumping with oil (diesel in thisExample) relative to pumping with formation water (Simulated FormationBrine or SFB) flowing through the pack. This graph demonstrates that thepack exhibits high flow resistance for water and low flow resistance foroil.

FIG. 2 compares the pressure differentials between the base proppant(not coated—depicted in gray) and the polymer-coated proppant packs (inblack, which is the beginning part of FIG. 1). This comparison was alsoconducted at 200° F. (93° C.) with diesel and simulated formation brine(SFB). The proppants are the same for each type, and the coated proppantwas prepared by the method previously described. It may be readily seenthat the VF-1 coated proppant was much more effective at controllingwater flow than the conventional, non-coated proppant.

More conventionally, RPM polymers are leaked-off into the formation toselectively control water flow, in one non-limiting instance asdescribed by E. G. Borodin, et al. in “Application of RelativePermeability Modifiers to Control Water Cut Following HydraulicFracturing in Western Siberian Oil Fields—Russian Case-History Study,”SPE 102679, 2006 SPE Annual Technical Conference and Exhibition, SanAntonio, Tex., 24-27 Sep. 2006, pp. 411-418. Instead, the compositionsand method described herein involve using RPM polymer coated ontoproppants in fractures to control water.

In the foregoing specification, the invention has been described withreference to specific embodiments thereof, and has been demonstrated aseffective in providing methods for inhibiting and controlling waterproduction from subterranean formations, particularly where the treatingfluid includes particles coated with relative permeability modifiers.However, it will be evident that various modifications and changes canbe made thereto without departing from the broader spirit or scope ofthe invention as set forth in the appended claims. Accordingly, thespecification is to be regarded in an illustrative rather than arestrictive sense. For example, specific combinations of particles,proppants and/or gravels with certain specific RPMs, mixing liquids andcarrier fluids and other components falling within the claimedparameters, but not specifically identified or tried in a particularcomposition or method, are anticipated to be within the scope of thisinvention. Further, it is expected that the components and proportionsof the particles, RPMs and fluids may change somewhat from one fluid toanother and still accomplish the stated purposes and goals of themethods described herein.

The words “comprising” and “comprises” as used throughout the claims isinterpreted “including but not limited to”.

The present invention may suitably comprise, consist or consistessentially of the elements disclosed and may be practiced in theabsence of an element not disclosed.

What is claimed is:
 1. Treated particles comprising: a plurality ofparticles selected from the group consisting of glass beads, ceramicbeads, metal beads, bauxite grains, walnut shell fragments, aluminumpellets, nylon pellets and combinations thereof, where the particlesrange in size from about 10 mesh to about 200 mesh (from about 2000microns to about 75 microns); and a relative permeability modifier (RPM)coated on the particles, where the RPM is a water hydrolyzable polymerselected from the group consisting of: homopolymers and copolymers ofacrylamide, sulfonated or quaternized homopolymers and copolymers ofacrylamide, polyvinylalcohols, polysiloxanes, hydrophilic natural gumpolymers and chemically modified derivatives thereof; crosslinkedhomopolymers and copolymers of acrylamide, crosslinked sulfonated orquaternized homopolymers and copolymers of acrylamide, crosslinkedpolyvinylalcohols, crosslinked polysiloxanes, crosslinked hydrophilicnatural gum polymers and chemically modified derivatives thereof;copolymers having a hydrophilic monomeric unit, where the hydrophilicmonomeric unit is selected from the group consisting of ammonium andalkali metal salt of acrylamidomethylpropanesulfonic acid, a firstanchoring monomeric unit based on N-vinylformamide and a fillermonomeric unit, where the filler monomeric unit is selected from thegroup consisting of acrylamide and methylacrylamide; and copolymers ofvinylamide monomers and monomers containing ammonium or quaternaryammonium moieties, copolymers of vinylamide monomers and monomerscomprising vinylcarboxylic acid monomers and/or vinylsulfonic acidmonomers, and salts thereof, and these copolymers comprising acrosslinking monomer selected from the group consisting ofbis-acrylamide, diallylamine, N,N-diallylacrylamide, divinyloxyethane,divinyldimethylsilane; where RPM loading ranges from one pound of RPMper about 100 to about 5000 pounds of particles (1 kilogram of RPM perabout 100 to about 5000 kilograms of particles).
 2. The treatedparticles of claim 1 where the treated particles are made by coating theparticles with the RPM by a process comprising: at least partiallyhydrolyzing the RPM in a liquid selected from the group consisting ofwater, brine, glycol, ethanol and mixtures thereof; contacting theparticles with the liquid; and at least partially vaporizing the liquid.3. The treated particles of claim 1 where the RPM is a waterhydrolyzable polymer having a weight average molecular weight greaterthan 100,000.
 4. The treated particles of claim 1 where the waterhydrolyzable polymer is a crosslinked water hydrolyzable polymerselected from the group consisting of: crosslinked polysiloxanes; andcopolymers of vinylamide monomers and monomers containing ammonium orquaternary ammonium moieties, copolymers of vinylamide monomers andmonomers comprising vinylcarboxylic acid monomers and/or vinylsulfonicacid monomers, and salts thereof, and wherein these vinyl amidecopolymers comprise a crosslinking monomer selected from the groupconsisting of-diallylamine, N,N-diallylacrylamide, divinyloxyethane, anddivinyldimethylsilane.
 5. Treated particles comprising: a plurality ofparticles selected from the group consisting of glass beads, ceramicbeads, metal beads, bauxite grains, walnut shell fragments, aluminumpellets, nylon pellets and combinations thereof, where the particlesrange in size from about 10 mesh to about 200 mesh (from about 2000microns to about 75 microns); and a relative permeability modifier (RPM)coated on the particles, where the RPM has a weight average molecularweight greater than 100,000. is a water hydrolyzable polymer selectedfrom the group consisting of: homopolymers and copolymers of acrylamide,sulfonated or quaternized homopolymers and copolymers of acrylamide,polyvinylalcohols, polysiloxanes, hydrophilic natural gum polymers andchemically modified derivatives thereof; crosslinked homopolymers andcopolymers of acrylamide, crosslinked sulfonated or quaternizedhomopolymers and copolymers of acrylamide, crosslinkedpolyvinylalcohols, crosslinked polysiloxanes, crosslinked hydrophilicnatural gum polymers and chemically modified derivatives thereof;copolymers having a hydrophilic monomeric unit, where the hydrophilicmonomeric unit is selected from the group consisting of ammonium andalkali metal salt of acrylamidomethylpropanesulfonic acid, a firstanchoring monomeric unit based on N-vinylformamide and a fillermonomeric unit, where the filler monomeric unit is selected from thegroup consisting of acrylamide and methylacrylamide; and copolymers ofvinylamide monomers and monomers containing ammonium or quaternaryammonium moieties, copolymers of vinylamide monomers and monomerscomprising vinylcarboxylic acid monomers and/or vinylsulfonic acidmonomers, and salts thereof, and these copolymers comprising acrosslinking monomer selected from the group consisting ofbis-acrylamide, diallylamine, N,N-diallylacrylamide, divinyloxyethane,divinyldimethylsilane; where RPM loading ranges from one pound of RPMper about 100 to about 5000 pounds of particles (1 kilogram of RPM perabout 100 to about 5000 kilograms of particles); and where the treatedparticles are made by coating the particles with the RPM by a processcomprising: at least partially hydrolyzing the RPM in a liquid selectedfrom the group consisting of water, brine, glycol, ethanol and mixturesthereof; contacting the particles with the liquid; and at leastpartially vaporizing the liquid.
 6. The treated particles of claim 5where the water hydrolyzable polymer is a crosslinked water hydrolyzablepolymer selected from the group consisting of: crosslinkedpolysiloxanes; and copolymers of vinylamide monomers and monomerscontaining ammonium or quaternary ammonium moieties, copolymers ofvinylamide monomers and monomers comprising vinylcarboxylic acidmonomers and/or vinylsulfonic acid monomers, and salts thereof, andwherein these vinyl amide copolymers comprise a crosslinking monomerselected from the group consisting of-diallylamine,N,N-diallylacrylamide, divinyloxyethane, and divinyldimethylsilane. 7.Treated particles comprising: a plurality of particles selected from thegroup consisting of glass beads, ceramic beads, metal beads, bauxitegrains, walnut shell fragments, aluminum pellets, nylon pellets andcombinations thereof, where the particles range in size from about 10mesh to about 200 mesh (from about 2000 microns to about 75 microns);and a relative permeability modifier (RPM) coated on the particles,where the RPM is a crosslinked water hydrolyzable polymer selected fromthe group consisting of: crosslinked polysiloxanes; and copolymers ofvinylamide monomers and monomers containing ammonium or quaternaryammonium moieties, copolymers of vinylamide monomers and monomerscomprising vinylcarboxylic acid monomers and/or vinylsulfonic acidmonomers, and salts thereof, and wherein these vinyl amide copolymerscomprise a crosslinking monomer selected from the group consistingof-diallylamine, N,N-diallylacrylamide, divinyloxyethane, anddivinyldimethylsilane; where RPM loading ranges from one pound of RPMper about 100 to about 5000 pounds of particles (1 kilogram of RPM perabout 100 to about 5000 kilograms of particles), and where the treatedparticles are made by coating the particles with the RPM by a processcomprising: at least partially hydrolyzing the RPM in a liquid selectedfrom the group consisting of water, brine, glycol, ethanol and mixturesthereof; contacting the particles with the liquid; and at leastpartially vaporizing the liquid.
 8. The treated particles of claim 7where the RPM is a water hydrolyzable polymer having a weight averagemolecular weight greater than 100,000.